At just the point in the 2015 festive calendar when most of us subsided into a coma, something bizarre happened. Thousands upon thousands of viewers on the streaming service Netflix tried out a new programme called Making a Murderer - a 10-part documentary series about justice gone awry, made available in its entirety on December 18 - and wound up binge-watching it from start to finish.

At just the point in the 2015 festive calendar when most of us subsided into a coma, something bizarre happened. Thousands upon thousands of viewers on the streaming service Netflix tried out a new programme called Making a Murderer - a 10-part documentary series about justice gone awry, made available in its entirety on December 18 - and wound up binge-watching it from start to finish.

Some paced themselves over a day or three. Some stayed up all night, hanging breathlessly on forensic details till dawn broke: blood swabs in a discarded SUV. Aerial photographs of a vast, rusted car graveyard. Stick-drawings of trailer interiors coaxed by an underhand defence investigator.

On the face of things, Making a Murderer looks like the televisual equivalent of last year's hugely talked-about podcast Serial - which reopened the case of a 1999 murder of a high-school student in Baltimore, and became the most popular podcast in the history of the format. At heart, though, this one is a slow-burning courtroom drama, taking us inside the trials of two men - Wisconsin car-salvage worker Steven Avery and his nephew, 16-year-old Brendan Dassey - who are charged with the abduction, rape and murder of a photographer called Teresa Halbach in October 2005.

The background to the crime is extraordinary: Avery had been released from prison two years earlier, after DNA evidence exonerated him from a previous sexual assault charge for which he'd already served 18 years. He was making a claim for damages of $36m at the time of his arrest.

The possibility that Avery may not have committed the murder of Halbach is what makes the series so engrossing, but according to the show's two directors, Laura Ricciardi and Moira Demos, it is not the reason why it was made.

"The question of guilt or innocence was never our question. We chose Steven Avery as our protagonist because of this unique and valuable window we thought he could offer on to the American criminal justice system."

The result has been startling. Since the show's climax, more than 300,000 people to date have signed a petition calling Avery's prosecution "an abomination of due process" and demanding his pardon. This week those pleas faced a setback when Wisconsin Governor Scott Walker said there would be no such amnesty.

Public enthusiasm for following this kind of serpentine real-life murder mystery has been strikingly apparent lately. Along with Serial, Andrew Jarecki's six-part HBO series The Jinx, which aired last year, looked at the extraordinary knack of US millionaire Robert Durst for winding up in close proximity to unsolved killings.

Unlike Ricciardi and Demos, the "authors" of both these other programmes - Jarecki, and Serial's host and executive producer Sarah Koenig - interposed themselves in the material overtly, essentially taking on the role of investigative reporters.

While Making a Murderer's account of the Avery trial provides plenty of fodder for armchair sleuths, the remit of the filmmakers is more rigorous: it's specifically to expose the gaping holes in the prosecution's case against Avery.

"Steven had been wrongly convicted in the mid-1980s, the system had clearly failed him," said Ricciardi and Demos. "In the intervening 20 years, there have been developments with DNA, there's been legislative reform, talk of wrongful convictions as a thing of the past, because now we have better science. And here he was, thrown back into this system. It was an opportunity to ask: has the system improved, and where are we now?"

What's inarguable is that, in presenting the myriad details of the case, the directors have made highly sophisticated TV. The legal proceedings have their share of cliffhangers and revelations, making the programme the long-form TV equivalent of a doorstop thriller that's hard to put down. But what we don't get is the luridly sensationalised style of true-crime reportage long familiar from the paperback genre, or from the blaring, headline-grabbing excesses of American network TV.

Making a Murderer could not have come out of Ireland or the UK. In Britain, courtrooms have only just recently started allowing fixed cameras inside, and roughly four of these 10 hours are excerpts from the Avery and Dassey trials nearly a decade ago.

But in 2013, Channel 4 edited a six-week case at Edinburgh's High Court into a two-hour documentary called The Murder Trial. Fly-on-the-wall procedural documentaries, such as BBC Two's The Detectives, about the sex crimes unit in Salford, are also on the rise.

What's likely to qualify Making a Murderer as especially influential is that it adds up to more than edge-of-your-seat television - it functions as eye-opening advocacy about the dangers of what one of Avery's defence lawyers, Dean Strang, calls "unwarranted certitude".

The same kind of prosecution thinking - bang up some likely suspects, then twist the case to fit their involvement - led to one of the most famous miscarriages of justice in recent US history, the imprisonment of a trio of West Memphis teenagers for the deaths of three children in 1993. Their case, a miasma of circumstantial evidence, hearsay and character assassination, was first addressed in the 1996 feature documentary Paradise Lost, and the saga of their appeals and eventual release was charted in two sequels.

Ricciardi and Demos talk of Paradise Lost as a vital touchstone: "Clearly audiences felt passionately about what they witnessed and got involved. But the tools available to those audiences are different today.

"They have social media, they have online petitions, Facebook, Twitter."

The true crime in Making a Murderer, at the end of the day, isn't just Halbach's murder - it's very possibly a crime, or in fact a whole cartload, perpetrated by the state of Wisconsin, in its haste to secure an alarmingly dubious set of convictions. Not only are these malfeasances disturbing in themselves, but they open up horrifying possibilities about what depths local law enforcement may have plumbed to get their man. If it was a frame-up, who exactly was involved? Like ITV's 2014 drama The Lost Honour of Christopher Jefferies, about the Bristol landlord who was dragged into the centre of the storm surrounding the disappearance and murder of his tenant, Joanna Yeates, it's about the vilification of a suspect potentially blinding the legal process. The OJ Simpson trial hinged in very much the same way on problems of inept prosecution: this, too, has been recreated, in the forthcoming 10-part FX series American Crime Story.

Are we ready to rip that particular can of worms back open? Sifting through all the Simpson trial testimony about mishandled DNA and accusations of planting will no doubt provoke a firestorm of conspiracy theories. True crime, after all, is hardly ever wrapped up as neatly as a Poirot mystery: getting to the truth is more often a murky business, and degrees of certainty can rarely be absolute.

These series insist on the crucial difference between suspects and murderers, and on the presumption of innocence as a dangerous precept to tinker with. They get us through the door with a sense of injustice and the promise of finding out whodunnit. But it's in forcing us to sift the evidence and realise the complexity involved in reaching a conclusion that they become so compelling.